Re: [Groff] widow/orphan control

[Tadziu Hoffmann]

> > If you prefer to have paragraphs demarcated by
> > blank lines, you can set the blank line macro
> > 
> > .blm pp
> > 
> > but then *all* blank lines would start a new paragraph.
> 
> Not necessarily.  Just use the `.ns' request to disable
> further spacing if there are multiple blank lines.

Sorry, this is a misunderstanding.  You're right if all the
paragraph macro did was to space forward a little.  But what
about things the paragraph macro might do additionally (such as
perhaps incrementing a counter and inserting a little number in
the margin for numbered paragraphs (if anybody cared for such
things))?  This would be triggered by any blank *input* line.

However, often you would want a blank line to mean a blank line
(for example, in source code fragments), and then you'd have to
explicitly turn the blank-line -> pargagraph translation off at
the beginning and back on at the end.

> You are right, I won't change this.  Instead, I'll probably
> activate the widow protection support in gtroff (see the
> WIDOW_CONTROL macro in the source files).  The basic idea is
> to save the last (formatted) output line(s) and defer its
> output if necessary -- a kind of built-in diversion.

I'm curious.  Doesn't the notion of "widow" require the concept
of what a "paragraph" is?  This goes far beyond the traditional
one-line-at-a-time typesetting of troff (unless augmented by
macros).  How will troff know what I consider a paragraph?

> For example, the effect of `.ns' invoked in a header macro is
> delayed until saved lines are already output.

I don't understand.  Isn't that how it's supposed to be?